Melphalan Cimetidine

CIMETIDINE MELPHALAN L plasma concentrations and bioavailability of melphalan by 30% and risk of poor therapeutic response to melphalan Cimetidine causes a change in gastric pH, which 1 absorption of melphalan Avoid concurrent use... 

A study in 8 patients with multiple myeloma or monoclonal gammopathy showed that pretreatment with cimetidine 1 g daily for 6 days reduced the bioavailability of a 10-mg oral dose of melphalan by 30%. The melphalan half-life was reduced from 1.94 to 1.57 hours. The interindividual variation in melphalan pharmacokinetics was high. Note that, because of the variability in melphalan absorption, the dose of oral melphalan is usually cautiously increased until myelosuppression is seen, to ensure therapeutic levels. Therefore, this modest interaction with cimetidine is unlikely to have many clinical consequences. 

Sviland L, Robinson A, Proctor SJ, Bateman DN. Interaction of cimetidine with oral melphalan. Cancer Chemother Pharmacol (1987) 20,173-5. 

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